1. Field of the Invention
The present invention relates to an indoor mobile communication device such as a cordless telephone and the like, more specifically, to improved technology providing for a simple structure, small fading effect, and stable communication.
2. Description of the Related Art
In indoor mobile communication devices such as cordless telephones and the like, the positions of communicating parties are not constant and the indoor environment, for example, the size of rooms can change. For those reasons it is necessary that the devices have a structure allowing for the reception of electromagnetic waves arriving from a variety of directions and for the transmission of electromagnetic waves in all direction. In prior art, vertical linear antennas, which are nondirectional in a horizontal plane, have been widely used.
However, in indoor mobile communication devices using a high frequency, the antennas become small because of a short wavelength. In such a case, however, the effective length of nondirectional antennas is decreased and the range in which communication is possible is narrowed. Furthermore, if electromagnetic waves that have passed various propagation paths in the indoor environment are received, the reception is affected by fading and stable communication is difficult to conduct. Furthermore, systems conducting communication by switching directivity have also been suggested, but such systems are complex and expensive.
Accordingly, it is an object of the present invention to provide an indoor mobile communications device having a simple structure, providing a sufficient range in which communication is possible, and also providing for stable communication with a small fading effect.